1. Field of the Invention
The present invention generally relates to manual clamps, and more particularly, relates to a manual toggle locking pull action clamp.
2. Description of Related Art
Manual clamps including pull action clamps and toggle locking action clamps have been known for numerous years. Prior art toggle clamps may include an extension of folded sheet metal riveted to both sides of a central handle housing, which has a pivoted latch element and leaf spring reacting against surfaces of the handle to preposition the latch for engaging a base mounted latch pin upon actuating the clamp handle to a clamping position. These prior art clamps are also simple to release by manual finger activation of a lever. Other prior art toggle clamps may use a locking means that include a flat leaf spring lock welded to the handle that is released by a trigger member.
Many of these prior art over center toggle locking action clamps are ideally suited for holding against heavy forces such as those generated in plastic molding operations or the like. These clamps are ideal for quick clamping of doors, lids, access covers on drums, containers or other vessels. Generally, these clamps work with a latch or bracket mechanism that engages a latch plate located on a door or the like. When the prior art clamps are in the open position, the latch or bracket is placed over the latch plate and then the handle is pushed in a downward motion until the clamp toggles onto an over center position. This will lock the clamp in position and lock the door or access cover to the body being clamped. Generally, the prior art clamps require two hands to operate these manual clamps. There have been some prior art clamps that have attempted to create one hand action for opening and closing of the clamps.
Many of these manual prior art clamps operate satisfactorily but are frequently subjected to environments of vibration, inverted positioning, and other harsh industrial environments. Therefore, many of the prior art clamps require both of the user's hands to open the clamp, i.e., one hand is needed to operate the clamp lever while the other is needed for pulling back the latch element on the clamp. Hence, there is a need in the art for an improved manual pull action clamp that is capable of one-handed operation in the work environment while also providing for an automatic retraction of a latch or bracket mechanism from the latch plate without use of the operator or user's second hand. There also is a need in the prior art for an improved manual pull action clamp.